tree 4b5425c6890b245ea428ba6bb7b872a3c0a611d4
parent 7bf2f6a30d1851c530ad5e4ee7e5c45fb6be0128
author Xin Long <lucien.xin@gmail.com> 1634730166 -0400
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1635874006 +0100

sctp: add vtag check in sctp_sf_do_8_5_1_E_sa

[ Upstream commit ef16b1734f0a176277b7bb9c71a6d977a6ef3998 ]

sctp_sf_do_8_5_1_E_sa() is called when processing SHUTDOWN_ACK chunk
in cookie_wait and cookie_echoed state.

The vtag in the chunk's sctphdr should be verified, otherwise, as
later in chunk length check, it may send abort with the existent
asoc's vtag, which can be exploited by one to cook a malicious
chunk to terminate a SCTP asoc.

Note that when fails to verify the vtag from SHUTDOWN-ACK chunk,
SHUTDOWN COMPLETE message will still be sent back to peer, but
with the vtag from SHUTDOWN-ACK chunk, as said in 5) of
rfc4960#section-8.4.

While at it, also remove the unnecessary chunk length check from
sctp_sf_shut_8_4_5(), as it's already done in both places where
it calls sctp_sf_shut_8_4_5().

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>